Apparatus for magnetic separation.



No. 739,741.' PATENTBD SEPT. 22, 41903.

- B. n. SWEET., APPARATUS POR'MAGNP'PIG SEPARATION. .APPLIUATIOl FILM? JUNE 14, 1902.

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110.739,741. PATENTE) smmza, 190s.-

l B. H. SWEET. APPARATUS FoR-MAGNBTIG SEPARATION.

' APPLICATION FILED JUNE 14'. 1902.

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u INVENTOR ivo. 739;?41.

s UNITED STATESV A l' latented September 22, 190g. PATENT OFFICE.

BENJAMIN Il'. SWEET, vOF BROOKLYN, NEX/V YORK.

APPARATUS FOR MAGNETIC sEP'ARATioN.

SPECIFICATION forming part of Leners Patent No. 739,741, dated september 22, 190s.

Application iiled June 14, 1902.

To @ZZ whom it may concern:

Be it known that I, BENJAMIN H. SWEET, a citizen of the United States, residing inthe borough of Brooklyn, in the city and State ot'y New York, (with a post-office address at 260 West Broadway, in the borough of Manhattan,) have invented certain new and useful' p Improvements in Apparatus for Magnetic' Separation, of which the following isa full and true description. y

The object of my invention is toprovide a simple form of apparatus for economically and speedily effecting a thorough separation of magnetic material from non-magnetic material or of highly-magnetic material from feebly-magnetic material. Y

My new apparatusis provided with means for feeding the ore mixture upon a magnet'- ized conveyor passing through the magnetic field formed between opposing pole-pieces. By this means magnetic particles will be' caused to adhere to the conveyor, and nonmagnetic and lessmagnetic particles and also sometimes highly magnetic particles are thrown o by the centrif ugalforce ofthe first conveyor onto the surface of a second con. veyer, which then passes this mixture through the opposite side of the field. The magnetic particles are thus separated from ,non-mag# netic particles, and thenV the magnetic particles adhering to both conveyers are carried out of the field, while the remainder of the ore mixture is delivered at a separate" point by gravity. v

In order to facilitate or. render more complete the separation of the two grades of particles, I employ magnetic attraction to eiect.

a preliminary separation of highly-magnetic particles from the ore mixture, whereby the mixture is fed upon the first-named conveyor in layers or sheets, the magnetic Vlayer being next to the surface of the conveyor, while the non-magnetic or feebly-maguetic layer is fed abovthe layer just mentioned. By this meansbut a small portion', Vit' any, of the highly-magnetic particles will be thrown oi from the first conveyor by the centrifugal force, such particles being first fed upon the conveyor at a point nearest tothe pole-piece.

5o .Asv hereinafter described,the separation may sean No. 111,638. (No moana also be -facilitated by employing devices which agitato the particles thrown oi from the first-named conveyor as they are passing through the iield, whereby all magnetizable particles, either highly or feebly magnetic, .willbe subjected to the action of the attractive force.

Referring to the accompanying drawings, in which similar letters indicate like parts in the several views, Figure l is a side view of a novel form of machine which may be employed by me in carrying out my new method. Fig. 2 represen ts a vertical section of said machine. Fig. 3 is a vertical section of a modilied form of my novel magnetic separator.

The preferred form of my apparatus, as'

shown in Fig. 2, is provided with a hopper A, haviuga discharge-opening in its bottom and means for regulating the discharge of the crushed ore mixture. This mixture may be discharged directly upon the surface of the upper conveyor of a pair of conveyors, which carry the mixture through the magnetic ield; but I prefer that the ore mixture shall be fed from the hopper upon acylinderorother device B, which passes through an auxiliary mag-` netic field energized in a suitable way-as, for instance, by an inductively-magnetized bar C, placed within the cylinder B.V When the device B is employed, a preliminary separation of magnetic from non-magnetic'or feeblymagnetic particles is effected by reason of the fact that the cylinder-B while passing through the field C will hold a considerable proportion of `the magnetic particles until they reach a point inline with the extremity of the pole of the magnet C, from which point they will fall upon the conveyor. The unattracted particleswill have fallen away from the'cylinder by gravity or will be thrown therefrom by the slight centrifugal force developed by said cylinder. The particles attracted by the cylinder B will fall at about the'point e, Fig. 2, and upon the exterior of the magnetizable drum, cylinder, or other conveyor E and'will form thereon a sheet or layer of magnetic material. As the said conveyor is moved the particles not attracted by the preliminary separator B will fall upon and form a layer over the magnetic layer, whereupon magnetic particles of the top layer will be attracted and held upon the surface of conveyer E and bythe attraction of the lower layerand of the conveyer.

In place of the preliminary separator illustrated and described any suitable form of device which will effecta preliminary separation of the ore mixture may be employed.

In order to make sure that the unattracted particles delivered by the cylinder B will all fall upon the conveyer E, I may provide a non-magnetic deflecting-plate or other device D, and the particles which slide from the surface of the cylinderB or are thrown therefrom by centrifugal force will strike against said device D and be deflected back to the surface of the conveyer E. This last-mentioned conveyer is driven at a comparatively high speed, such high speed increasing the capacity o f the machine and also developing considerable centrifugal force. This results in throwing off from the periphery of the cylinder or drum E the lunattracted particles, leaving adhering thereto the magnetic particles, including those delivered ate and those extracted from the mixture which had passed over the cylinder B without separation. The unattracted material thrown off by the centrifugal-force of the conveyer E is in the preferred form of my apparatus. kept in the inagnetic field for the extraction therefrom of any unattracted magnetic particles retained by the expelled mixture. For this purpose I provide the machine with a second magnetizable conveyer I, upon which said expelled mixture is received and which reconveys the same through the magnetic field. This conveyer I may be of any suitable type; butI prefer a drum or cylinder movingin the saine direction through the field as the conveyer E. In order to guide the mixture thrown off by the conveyer E onto the periphery of the conveyer I, I prefer to provide a defiector H, of non-magnetic material and located in such position as to guide the expelled mixture downward to the periphery of I, with the -result that such mixture is agitated and deflected upon conveyer I in the form of a tumbling layer or sheet, subjecting all of the magnetic particles to the attractive action of the magnetic field.

The conveyerI is preferably moved through the field at a speed which is less than that of` the conveyer E and preferably at such a speed that it does not throw olf the material by centrifugal force. The unattracted particles will therefore slide upon the periphery of the cylinder I until they reach such a point that they fall therefrom by gravity.

An especially novel feature of my invention resides in so disposing the conveyers as to have one of said conveyers or a portion thereof pass underneath the other conveyer, one such arrangement being shown in the accompanying drawings. The particular advantage arising from disposing the conveyers in this relation to each other is that any unattracted particles which are not thrown off by the centrifugal action of the conveyer E will fall by gravity across the field-and then into contact with the second conveyer and will be again carried through the field. This will greatly assist in the attraction and separation ofv attractable particles contained in the mixture, owing to the fact that these particles pass twice through the field. The magnetic particles which adhere to the periphery of the drum or cylinder E are carried thereby until they reach a point beyond the extremity of the field, when such magnetic particles Vwill drop and be guided away by a non-magnetic plate L into a suitable receptacle. At the speed at which conveyer I is preferably driven in practical operation the magnetic particlesl which adhere to this conveyer I will similarly be carried out of the field and will fall into a receptacle Q, while the feebly-magnetic particles carried by the cylinder I will fall off therefrom at a point which permits them to be caught in a receptacle P. As I have heretofore stated, the speed of conveyer I will preferably be so slowasto develop little, if any, centrifugal force. In order to prevent the unattracted particles from being thrown ofrom said cylinder, as well as to cause them to be agitated or stirred during their passage through that part of the field, I mayprovide a series of non-metallic plates N, Fig. 2, all ot' which may be secured to an upright M, and against these plates will fall the unattracted particles which roll off or are thrown from the cylinder I. These particles fall from .plate to plate, rolling over the edge of each and being thereby constantly tumbled, with the resultthat the magnetic particles therein are exposed to the action of the field and are withdrawn from the mixture to the periphery of the conveyer I and then carried overto the receptacle P or to the receptacle Q.

My invention is not confined to the ernploymentof a single pair of separating cylinders or conveyers, and in order to completely separate all of the magnetic particles from the mixture any number of successive conveyers and fields may be employed. In Fig. 3 I have shown an apparatus having three conveyers placed at dierent levels, a portion of the conveyer I passing underneath the conveyer E and a portion of the third conveyer R passing underneath conveyer I,

whereby the ore mixture may be repeatedly subjected to magnetic attraction before passing out of the apparatus. The magnetic field `or fields may be formed between any suitable terminals. I prefer, however, to arrange the pole-pieces Within the cylinder. As shown in Fig. 1, the magnet core or cores T may be outside of the cylinders or may be placed `within the sameas shown in Fig. 3. In

either construction I prefer to provide the pole-pieces withextended surfaces or wings F or J, connected to the core extensions G K, Fig. 2, or to the cores X X' X2, Fig. 3. In the latter figure the yokes Y Y' Y2 are also shown as being placed within the cylinder.

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The feeding cylinder or drum B when it is used for eecting the preliminary separation hereinabove described may be' magnetized in any desired way, as by induction, or a separate coil may be employed for this purpose.

What I claim isl. In a magnetic separator, pole-pieces separated by an interval constituting a magnetic field, a magnetizable cylinder surrounding one pole-piece, a second magnetizable cylinder moving at a lower speed and surrounding the other pole-piece, the periphery of the second-named cylinder passing below a portion of the first cylinder, and a delecting device for assuring the delivery -upon the lower cylinder of the particles thrown oi by centrifugal force from the upper cylinder, substantially as described.

2. Ina magnetic separator, pole-pieces separated by an interval constituting a magnetic field, a magnetizable cylinder surrounding one pole-piece, a second magnetizablecylinder moving at a lower speed and surrounding the other pole-piece, the periphery of the second cylinder passing underneath a portion of the rst cylinder; a device for feeding a mixture containing magnetic particles upon the upper cylinder, said device adapted to preliminarily separate magnetic particles from the mixture, a detlecting device for assuring the delivery upon the lower cylinder of the particles thrown ed by centrifugal force from the upper cylinder, and means for causing agitation of the non-attracted particles while passing through the eld, substantially as described.

3. In a magnetic separator, a pair of rotaposed magnetic bodies separated by an interval constituting a magnetic field, a rotatable magnetizable cylinder inclosing each body, one cylinder moving at a lower speed than the other, a feed device for delivering ore mixture upon the higher-speed cylinder, and

meansA for dedecting to the upper surface of the lower-speed cylinder the material discharged from the higher-speed cylinder by centrifugal force, substantially as described.

5. In a magnetic separator, oppositely-disposed magnetic bodies separated by an interval constituting a magnetic eld, a rotating magnetizable cylinder inclosing each body, means for feeding ore mixture upon one cylinder, means for feeding material not attracted by the first cylinder to the second cylinder, and defiecting devicesfor re-presenting to each cylinder the material not previously attracted, substantially as described.

6. In a magnetic separator, a pair of rotatable magnetic cylinders separated by an interval constituting a magnetic eld, means for feeding ore mixture upon one cylinder, means for feeding the material not attracted by the rst cylinder to the second cylinder, and deflecting devices for re-presenting to each cylinder the material not previously attracted, substantially as described. l

7. In a magnetic separator, a pair of rotatable magnetic cylinders separated by an interval constituting a magnetic field of variable intensity, means for feeding ore mixture upon one cylinder at a point where the field is Weak, means for returning material,dis charged from said point of feed, to thecylinder at a point Where the eld is more intense,

means for delivering to the second cylinder within the field the material rejected by the first cylinder, and one or more devices for returning to the second cylinder Within the field the material rejected thereby, substantially as described.

In Witness whereof I have hereunto set my name this 10th day of June in the year 1902.

BENJAMIN H. SWEET. Witnesses:

JAMES J. Cosenovn, W. l-l. BERRIGAN, J r. 

